A conventional hand-held belt sander has a body segment, a sanding belt segment mounted to the body segment and rotatable about an axis relative to the body segment, and a positioning device configured in a way such that the sanding belt segment can be positioned relative to the body segment at a desired operating angle, so that sanding operation can be performed easily and conveniently in a relatively narrow working space, such as a groove or a bore.
In order to prevent undesired changes of the operating angle during the sanding operation, the positioning device typically includes a screw bolt that is screwed tightly into the sanding belt segment and the body segment of the conventional hand-held belt sander so as to prevent rotational movement of the sanding belt segment relative to the body segment, such as that disclosed in FIG. 1 of Japanese Patent No. 4017348, or in FIG. 1 of Japanese Patent No. 4154393.
However, the screw bolt of the positioning device may be loosed due to vibration of the conventional hand-held belt sander during the sanding operation, thereby creating safety concerns. Furthermore, the sanding belt segment may be separated from the body segment along the axis due to the vibration.